Cost Difference - Hydraulic v Electric Transmissions

[John M]

Going back to the original topic the Great Northern (Board) review of the 1st round of tenders for locos in the 875-1000hp power capacity provides a useful cost comparison of diesel electric and hydraulic types. The GNR specification for a lightweight (15t axleload) compact  (39' long) loco due to infrastructure constraints, effectively ruling out the majority of the diesel electric proposals and steam heating.

 

1. English Electric single and double cabbed 1000hp A1A-A1A £55,120-£62,940             l

2. NBL 1000hp B-B diesel hydraulic. More expensive than German MAK proposal.

3. Metropolitan Vickers 1200hp Co-Co £61,433            

4. Alsthom 1180-1250hp Bo Bo off the shelf Europeam design £41,700

5. GMOO 875-900 hp Bo Bo or A1A A1A £50,937 & £52,179 (GM G8 export model?)

6. Sulzer Bros (London) 1160hp Bo Bo £46,546  (Compact single cabbed hood unit)

7 MAK 1000HP B-B diesel hydraulic (double cabbed) £38,675 ( met spec)

8 Nydquist & Holm (Nohab)  A1A A1A £63,413 (European version of GMOO G12?)

9. Arn Jung 1000Hp B-B Maybach MD650 or Damlier Benz MB820 double cabbed  £38,675 

 

The Arn Jung loco was recommended both on the grounds of cost and the only loco that fully met the spec.

 

Interestingly the English Electric and Metrovick diesels were in a similar price range and substantially more expensive than a standard GM export model.

 

There appears to have been a high level of design co-ordination between German loco builders and component manufacturers with a high degree of engine and transmission inter-changability  between locos built by different manufacturers.

 

This would have both helped keep purchase and maintenance costs down, especially if maintenance was carried out on a component replacement basis.

 

 

[Pete the Elaner]

Surely maintenance costs were a bit of a mystery back then with both types of transmission being relatively new to the railways?

If you are going to try 2 different technologies, it would make sense to concentrate the less common type into a particular region so the fitters can specialise in 1 type, hence the hydraulics being concentrated on the WR. 

[cheesysmith]

If you are comparing the costs of hydraulic Vs electric locos, the only valid comparison is either the 21/22, both built by the same manufacturer or the westerns Vs the class 47, both built using stressed skin designs bodies. In both cases the hydraulic loco came out cheaper and lighter, but with the railways then being mixed traffic, the advantage of lighter locos for passenger work, and the track friendly advantages were not recognised (until the class 86s pounded the WCML to bits anyway). But BR has already worked out the overhaul costs of the loco engine was directly associated with how many cylinders the engine had. There was also the problem of locos with DC generators over 2000hp being more unreliable due to flash overs etc, the class 47&50s being at the limit of what was achievable. Also, a reason for the WR going hydraulic was to get away from the problems of maintaining the electrics along side the dirt of the steam locos. They had already had experience of these problems with the gas turbine locos, so the use of light engines and transmissions that were to be maintained on a component exchange basis, with all the work being done at Swindon, the depots undertaking the exchange and sending the components away, would enable them to avoid the problems of the steam and diesel mixing.

 

As history has proven, the electric transmission has unbeatable advantages in freight, with creap control able to provide unmatched haulage power, but in passenger use, to minimise the damage to the rack, the electric transmission has evolved to look like the hydraulic locos, with only the gearbox or final drive mounted on the axle, the simple and cheap direct axle mounted electric motor having been proven a bad idea at speed by the 86.